Techniques for spatial reuse in wireless personal area networks based on virtual time divisional multiple access

ABSTRACT

An embodiment of the present invention provides a method, comprising configuring a transceiver for special reuse using a virtual time division multiple access (TDMA) technique in a wireless personal area network that allows additional non-interfering transceivers to perform concurrent transmissions with said transceiver.

BACKGROUND

The availability of 76 Hz of unlicensed spectrum in the 60 GHz bandoffers the potential for multi-Gigabit indoor wireless personal areanetworking (WPAN). Applications that require large bandwidth includeuncompressed High Definition (HD) video streaming, fast file downloadfrom an airport kiosk (Sync & Go) and wireless display and docking, toname just a few. These applications cannot be supported over existinghome networking solutions (IEEE 802.11a/b/g/n and WiMedia UWB) becausethe required data rates far exceed the capabilities of these networks.

A mmwave communication link is less robust than those at lowerfrequencies (e.g. 2.4 GHz and 5 GHz bands) because of its inherentisolation due to both oxygen absorption, which attenuates the signalover long range, and its short wavelength, which provides highattenuation through obstructions such as walls and ceilings. Thus, oneof the biggest challenges for designing a high data rate radio systemfor the 60 GHz band is the limited link budget resulting from high pathloss during radio propagation. On the one hand, it is preferable toemploy directional antennas for high-speed point-to-point datatransmission. On the other hand, a directional antenna pattern coveringa wide range of angles to give omni-directional coverage is usuallyemployed to aid in neighbor discovery and beam-steering decisions. Alower band channel (e.g. IEEE 802.11 WLAN in 2.4 GHz or 5 GHz bands orWiMedia UWB in 6 GHz band) may be used as an out-of-band (OOB) controlchannel providing robust transmission and coverage.

Spatial reuse is the ability of the network to support concurrenttransmissions that depends on the network topology and individualtransmission ranges. Devices performing directional transmissions can beseparated in space such that certain pairs of devices can communicatesimultaneously. However, in a traditional 60 GHz wireless personal areanetwork (WPAN), the channel time is scheduled using Time DivisionMultiple Access (TDMA) technology that does not support paralleltrasmissions. Channel time reservations are usually performed for eachsuper-frame (the basic timing division for TDMA) and communicated in thebeacon frame(s) sent on the control channel as seen in FIG. 1 at 100.

Thus, a strong need exists for techniques for spatial reuse in wirelesspersonal area networks.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features, and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanying drawings in which:

FIG. 1 illustrates an example of a traditional TDMA mechanism;

FIG. 2 shows spatial reuse groups division in an embodiment of thepresent invention;

FIG. 3 depicts a proposed virtual TDMA mechanism in an embodiment of thepresent invention;

FIG. 4 depicts the message flow to evaluate the link compatibility in anembodiment of the present invention; and

FIG. 5 illustrates a wireless personal area network (WPAN) topology inan embodiment of the present invention

It will be appreciated that for simplicity and clarity of illustration,elements illustrated in the figures have not necessarily been drawn toscale. For example, the dimensions of some of the elements areexaggerated relative to other elements for clarity. Further, whereconsidered appropriate, reference numerals have been repeated among thefigures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components and circuitshave not been described in detail so as not to obscure the presentinvention.

Embodiments of the invention may be used in a variety of applications.Some embodiments of the invention may be used in conjunction withvarious devices and systems, for example, a transmitter, a receiver, atransceiver, a transmitter-receiver, a wireless communication station, awireless communication device, a wireless Access Point (AP), a modem, awireless modem, a Personal Computer (PC), a desktop computer, a mobilecomputer, a laptop computer, a notebook computer, a tablet computer, aserver computer, a handheld computer, a handheld device, a PersonalDigital Assistant (PDA) device or a handheld PDA device.

Although embodiments of the invention are not limited in this regard,discussions utilizing terms such as, for example, “processing,”“computing,” “calculating,” “determining,” “establishing”, “analyzing”,“checking”, or the like, may refer to operation(s) and/or process(es) ofa computer, a computing platform, a computing system, or otherelectronic computing device, that manipulate and/or transform datarepresented as physical (e.g., electronic) quantities within thecomputer's registers and/or memories into other data similarlyrepresented as physical quantities within the computer's registersand/or memories or other information storage medium that may storeinstructions to perform operations and/or processes.

Although embodiments of the invention are not limited in this regard,the terms “plurality” and “a plurality” as used herein may include, forexample, “multiple” or “two or more”. The terms “plurality” or “aplurality” may be used throughout the specification to describe two ormore components, devices, elements, units, parameters, or the like. Forexample, “a plurality of stations” may include two or more stations.

An embodiment of the present invention provides a virtual time divisionmultiple access (TDMA) scheme that allows non-interfering devices toperform concurrent transmissions. All links (transmitter/receiver [alsoreferred to herein as a transceiver] pairs of devices) may be dividedinto a number of groups so that a directional transmission of atransmitter in one group does not interfere with a receiver in adifferent group as shown generally as 200 of FIG. 2. Group 1 is shown at210 with transmitter (also referred to herein as transceiver) 1 andreceiver (also referred to herein as transceiver) 1 and group 2 at 205with transmitter (transceiver) 2 and receiver (transceiver) 2. The linksmay be either unidirectional or bidirectional. We denote the number ofsuch groups by k.

In this way, data transmissions may be scheduled independently usingTDMA on k virtual channels 320 as seen generally at 300 of FIG. 3.Superframe n−1 is shown at 305, superframe n at 310 and superframe n+1at 315. Data S1 to R1 is shown at 330 and data Sk to Rk is shown at 325.Under a centralized MAC (e.g. IEEE 802.15.3c), this subdivision can beperformed by the coordinator while under a distributed MAC (e.g. WiMediaUWB) such groups may be defined through negotiation between devices onthe control channel. In order to maximize the number of paralleltransmissions (that is the number of groups k), transmitting devices maydecrease the transmission power and/or change the beam-steeringpatterns. The scheduling of channel time reservations in differentgroups needs to be coordinated if a particular device participates inmultiple links falling into different groups so that this device is notscheduled in more than one group at a time.

To divide the links into groups, it is necessary to identify theinterference level caused by a transmitter (transceiver) at potentialvictim receivers (transceivers). The Coordinator under a centralized MACor each device under a distributed MAC constructs a table indicatingwhether the transmission of a particular device interferes with anexisting link. The compatibility table determines which links are ableto transmit simultaneously and shall be updated when the beam-steeringpattern changes or a devices moves to a new location. This table is usedto construct the spatial reuse groups, which allow simultaneoustransmissions in the WPAN thus achieving spatial reuse.

Turning now to FIG. 4 at 400 is illustrated the message flow of theinterference table calculation process, which is done with the aid of anout of band (OOB) control channel. FIG. 5 at 500 is used as an exampleof the WPAN topology with A, B, C, D, E shown as 510, 520, 530, 540 and550 respectively. It is understood that the topology of FIG. 5 is butone example topology and the present invention is not limited to thistopology. The first step is that the Coordinator 405 announces on theOOB control channel the time and the data channel used for thedirectional transmission of an existing link (e.g., bidirectional link A510<->B 520) 430. For a distributed MAC, the transmitting devices willannounce their directional transmissions individually. Then the rest ofthe devices (e.g., C 530, D 540 and E 550) will listen 435 for an amountof time sufficient to determine whether they can hear signal from eitherA 510 or B 520. If a device (e.g., C 530 and E 550) cannot hear thesignal, that means it is not affected by the link under consideration(e.g. C 530 and E 550 are outside the beam-width of A 510 and B 520 andC 530->E 550 transmission will not interfere with that of A 410<->B520). If a device can hear the signal, that means it is within thecoverage area of the link under consideration (e.g. D 540 is inside thebeam-width of B 520, thus D 540 will receive B's 520 transmission whenthe link A 510<->B 520 is active. As a consequence, if D 540 transmits,it will interferer B's 520 reception from A 510). Finally, the rest ofthe devices report their compatibility 440 and 445 with the link underconsideration to the Coordinator 405 through the OOB channel. Thisinformation is used to build 450 a compatibility table set forth below.At 455, A 510 and B 520 communicate on the designated channel and time.For a distributed MAC, no reporting is needed and each node evaluatesits own compatibility with the link under consideration.

TABLE 1 Links compatibility Compatible Devices Incompatible Devices (canreceive when the link (cannot receive when the is active) link isactive) Old Link 1 C and E D (A<−>B) New Link 2 A, B and D None (C−>E)

For example, the communication between C 530 and E 550 may be grantedconcurrently with A 510<->B 520 if requested since they do not interferewith each other. Henceforth, the links A 510<->B 520 and C 530->E 550belong to two different spatial reuse groups.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those skilled in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

1.-24. (canceled)
 25. A device comprising: a transceiver configured toengage in a directional communication with a receiving device in awireless network, wherein, to determine whether the directionalcommunication between the transceiver and the receiving deviceinterferes with another directional communication, the transceiver isfurther configured to: receive a notification from a coordinatorindicating one or more details of the other directional communication;based on the one or more details, determine, for a predetermined amountof time, whether or not the transceiver receives at least part of dataof the other directional communication; and transmit, to thecoordinator, a result of the determination, wherein a determinationresult indicating that the transceiver received at least part of data ofthe other directional communication indicates possible interferencebetween the directional communication and the other directionalcommunication, and a determination result indicating that thetransceiver did not receive at least part of data of the otherdirectional communication indicates no interference between thedirectional communication and the other directional communication. 26.The device of claim 25, wherein based on the determination result, thecoordinator is configured to manage compatibility information indicatingpossible simultaneous directional communication links in the wirelessnetwork.
 27. The device of claim 25, wherein the one or more details ofthe other directional communication include time, data channel, or both,associated with the other directional communication.
 28. The device ofclaim 25, wherein the transceiver is configured to receive thenotification, transmit the determination result, or both, on a controlchannel which is independent of a data channel supporting thedirectional communication or the other directional communication. 29.The device of claim 25, wherein in order to maximize a number ofsimultaneous directional communication links in the wireless network,transceiver is further configured to decrease a transmission power,change a beam-steering pattern, or both, associated with the directionalcommunication.
 30. The device of claim 25, wherein the transceiver isconfigured to engage in the directional communication with only onereceiving device at a time.
 31. The device of claim 25, wherein thedetermination result is dependent on a beam-steering pattern, or alocation, or both, of the transceiver.
 32. A method comprising:configuring a transceiver to engage in a directional communication witha receiving device in a wireless network; and determining whether thedirectional communication between the transceiver and the receivingdevice interferes with another directional communication, saiddetermining comprising: receiving a notification from a coordinatorindicating one or more details of the other directional communication;based on the one or more details, determining, for a predeterminedamount of time, whether or not the transceiver receives at least part ofdata of the other directional communication; and transmitting, to thecoordinator, a result of the determination, wherein a determinationresult indicating that the transceiver received at least part of data ofthe other directional communication indicates possible interferencebetween the directional communication and the other directionalcommunication, and a determination result indicating that thetransceiver did not receive at least part of data of the otherdirectional communication indicates no interference between thedirectional communication and the other directional communication, andwherein the determination result is used to manage compatibilityinformation indicating possible simultaneous directional communicationlinks in the wireless network.
 33. The method of claim 32, wherein theone or more details of the other directional communication include time,data channel, or both, associated with the other directionalcommunication.
 34. The method of claim 32, wherein said receiving anotification, said transmitting a determination result, or both utilizea control channel which is independent of a data channel supporting thedirectional communication or the other directional communication. 35.The method of claim 32, further comprising decreasing a transmissionpower, changing a beam-steering pattern, or both, associated with thedirectional communication in order to maximize a number of simultaneousdirectional communication links in the wireless network
 36. The methodof claim 32, wherein said configuring the transceiver to engage in thedirectional communication comprises configuring the transceiver toengage in the directional communication with only one receiving deviceat a time.
 37. The method of claim 32, wherein the determination resultis dependent on a beam-steering pattern, or a location, or both, of thetransceiver.
 38. A coordinating device comprising: a memory; and aprocessor configured to manage compatibility information indicatingpossible simultaneous non-interfering directional communication links ina wireless network, wherein to manage the compatibility information, theprocessor is further configured to: transmit a notification to at leastone transceiver in the wireless indicating one or more details of anexisting directional communication in the wireless network; receive,from the at least one transceiver, a result of a determinationindicating whether or not the at least one transceiver received at leastpart of data of the existing directional communication which indicateswhether or not interference is possible between a directionalcommunication associated with the at least one transceiver and theexisting directional communication; and update the compatibilityinformation in the memory based on the determination result.
 39. Thedevice of claim 38, wherein the one or more details of the existingdirectional communication include time, data channel, or both,associated with the existing directional communication.
 40. The deviceof claim 38, wherein the processor is configured to transmit thenotification, receive the determination result, or both, on a controlchannel which is independent of a data channel supporting thedirectional communication associated with the at least one transceiveror the existing directional communication
 41. The device of claim 38,wherein the determination result is dependent on a beam-steeringpattern, or a location, or both, of the at least one transceiver.
 42. Amethod comprising: managing compatibility information indicatingpossible simultaneous non-interfering directional communication links ina wireless network, said managing comprising: transmitting anotification to at least one transceiver in the wireless networkindicating one or more details of an existing directional communicationin the wireless network; receiving, from the at least one transceiver, aresult of a determination indicating whether or not the at least onetransceiver received at least part of data of the existing directionalcommunication which indicates whether or not interference is possiblebetween a directional communication associated with the at least onetransceiver and the existing directional communication; and updating thecompatibility information based on the determination result.
 43. Themethod of claim 42, wherein the one or more details of the existingdirectional communication include time, data channel, or both,associated with the existing directional communication.
 44. The methodof claim 42, wherein said transmitting a notification, said receiving adetermination result, or both utilize a control channel which isindependent of a data channel supporting the directional communicationassociated with the at least one transceiver or the existing directionalcommunication.